This invention provides a simple and practical method to improve the performance and life of a single-acting two piston Stirling engine without at the same time increasing its complexity or decreasing its mechanical efficiency.
It is generally agreed that the single-acting two piston Stirling engine is one of the most desirable forms of Stirling for small power applications, having demonstrated both simplicity and good performance. Such engines may be designed in a variety of forms; for example, cylinders may be arranged in a V, in-line, or horizontally opposed.
One of the most desirable arrangements is the V type engine, in which the cylinders are generally located radially off of a common crankpin and 90.degree. apart from each other. This arrangement provides mechanical simplicity and strength, proper piston phasing for the Stirling cycle, and excellent dynamic balance. There are, however, two related disadvantages of this arrangement, which are; 1) the pistons are side-loaded by the periodic angularity of the connecting rods, which can produce high wear and high friction in the preferred oil-less design unless long connecting rods are used, and, 2) as the connecting rods are made proportionally longer to reduce this side-loading, the cylinder heads become farther apart, requiring larger plenums and heat exchangers, with increased performance-robbing dead volume, to connect them. The designer who chooses efficient compact heat exchangers and connecting plenums will be left with poor performance due to short connecting rods, and the designer who chooses efficient long connecting rods will be left with poor performance due to large dead volume in the heat exchangers and associated plenums.
The aim of this invention is to disclose a new form of compression piston and cylinder that will allow the engine designer to incorporate both compact heat exchangers and plenums, and efficient long connecting rods, on the V type Stirling engine.
Other aims, features, and advantages will be apparent in the description, below.